Elevator systems are built into buildings. The former can include an elevator car which, via suspension ropes or suspension belts, is connected to a counterweight or to a second elevator car. By means of a drive, which can be chosen to act on the suspension means or directly on the car or counterweight, the car is moved along essentially vertical guiderails. The elevator system is used to transport persons and goods between one or more floors in the building.
The elevator system contains apparatus to secure the elevator car in case of failure of the drive, or of the suspension means, or to prevent undesired drifting away or falling when stopped at a floor. For this purpose, safety gears are generally used which, in case of need, can brake the elevator car on the guiderails.
Traditionally, such safety gears can be actuated by mechanical overspeed governors. Today, however, electronic monitoring devices are also increasingly used which, in case of need, can activate braking apparatus or safety gears. So as to be able nonetheless to rely on known and proven safety gears, electromechanical actuating units can be required which, when correspondingly triggered, can actuate safety gears.
From EP0543154 such a device is known. By its means, in case of need, an auxiliary caliper brake is brought into engagement with a guiderail, and this auxiliary caliper brake actuates an existing lever system, by means of which safety gears are actuated. This auxiliary caliper brake is designed to be able to move the lever system and mass components of the safety gear. The necessary electromagnetic units are dimensioned correspondingly large.
From U.S. Pat. No. 7,575,099 a further such device is known. In this solution, in case of need, engagement wedges of a safety gear are actuated directly by springs. The springs are pretensioned by an electromagnet and, in case of need, the pretensioned springs are released. The springs can be reset or retensioned again by means of a spindle drive. This electromagnet can be dimensioned correspondingly large, since the entire prestressed force of a plurality of springs should be absorbed and held.